GSN recently interviewed director David Yates. It was revealed that J. K. Rowling has already written the script for Fantastic Beasts and Where To Find Them 2 and has ideas for the final instalment.
"We've done the first one, she's written the second one, she's got ideas for the third one."
"No one quite has ownership of them quite yet, in terms of having a relationship with the material, other than the relationship they'll have with the movie when it comes out. So it's sort of lovely in a way."